Why It Matters Here
Kansas City gets ice storms in winter and strong thunderstorms in spring and summer, and both knock out power. Without a backup, a dead opener means pulling the red release cord and lifting the door by hand, which is heavy work and can leave the door unlocked until the power comes back. If the garage is how you get in and out of the house, a backup is worth having.
How It Works
A battery sits inside or next to the opener and stays charged from the outlet. When the power goes out, the opener switches to the battery and keeps working for a number of open and close cycles. It's built for getting you through an outage, not for running for days. The battery usually needs replacing every couple of years, and the opener beeps or flashes a light when it's getting weak.
Adding It to What You Have
Many LiftMaster openers have a slot for a backup battery, or come with one. Older openers usually can't take one, and the answer there is a new opener with backup built in. Zach will check your opener and tell you which applies. See opener installation for picking a new one.
Test It Once a Year
Unplug the opener and run the door once. If it opens and closes, you're set. Fall, before ice storm season, is a good time. The winter prep post has a few other checks worth doing at the same time.